Magazine Spring

Question
Dear Mr. Gore:

I have two magazine-fed firearms, a SigSauer P6 and a Ruger Mini14, with two magazines for each.  All of the magazines are about three years old.  These are my first, and only, magazine-fed guns.  I keep all magazines loaded continuously.  Recently, I have noticed articles that say that the spring will take a set if the magazine is kept loaded.  

If that is accurate, what is the minimum time to allow a magazine to be unloaded to prevent the set?  That is, can I unload a magazine and let it sit for a couple of hours before reloading, or is the minimum time more like a week or more?

If this question has been asked before, I apologize in advance.  My search of allexperts did not yield an answer.

Thank you for your service, especially for your previous answer about chambering an extra round.

Answer
it depends on when it was made, what  type of spring, how old or new the spring is, how long it was compressed before.

If a mag was loaded for two years it would be more compressed than one loaded for two months.

Most modern springs are better made and retain their spring longer and resist compression, older springs not as good or cheaper mags not as good as older mags.

I would say 6 months to a year I would unload and you can tell if the bullets are coming out with pressure or not.

I do this but most manufactures DO NOT recommend it, but I still do it. If I think my mag spring is a little compressed I will pull the spring to make it longer just a little to put more life back in the spring. Of course if you do this too much or too hard you will mess up the spring and do damage, but stretching it out a little seems to put it back to normal.

Probably the best thing is to make sure and buy good quality new springs and don't fully load the mag so the spring is not fully compressed and to unload the mag every couple of months for a day or so and be aware of the tension when you load and unload bullets, you should be able to tell if a mag loads too easy or easier than another mag for the same gun, the tension should be consistent.

I would think you could leave most mags loaded for a year or two they would still work fine, but you should firing and cleaning and using your guns more than once every two years so this should not be an issue.

My opinion.  :)